Vehicle-spring.



No. 857,256. PATENTBD JUNE 18, 1907.

' P. E. PRATT.

VEHIOLE SPRING. APPLICATION FILED MAR.21,1906.

I/vmvron WIT I Y a v 52 ATTORNEY.

NITED sTATEs PATENT oEEIoE.

FRANCIS EDWARD PRATT, or NEW RooHELLE, NEW YORK.-

VEHICLE-SPRING.

Specification of Letters Patent.

Patented June 18, 1907.

Application filed March 21, 1906. Serial N0- 307,251-

and preventing excessive vibration and breakage of the springs due to the sharp recoil of the ordinary form of spring when the wheel goes over a large obstruction.-

The best form of apparatus embodying my invention at present known to me is shown in the accompanying drawing which .is a side elevation of an apparatus embodying my invention, in which 1 represents the ordinary form of elliptical leaf spring composed of a series of upper leaves, 2, 3, 4, 5, 6, and a series of lower leaves, 7, 8, 9, 10, 11. The two sets of leaves are jointed at 12 and 13, so as to form an approximately elliptical structure. The spring of course supports the weight of the'vehicle on its upper side and rests u on the axle or similar support attached to t 1e wheel frame, all in the usual way.

On the inner sideof the upper leaf attached to the inner leaf 6 in any convenient manner, is a suitable bearing block 14, to which is pivoted in any convenient manner, two swinging links 15 and 16. In the same way, to the under section of the spring, the inner leaf l1 thereon is connected to the bear ing block 17. To this is pivoted the swinging links 18 and 19. The outer or free ends of the swinging links are connected together by short blocks 20 and 21. The said blocks are pivotally connected to the links so as to join the free ends of the opposite links.- These blocks 20 and 21 are connected together by a stiff powerful spiral spring 22 ex- .tending diagonally across the quadrilateral figure formed by the four swinging links. This spring 22 is preferably made in the shape of a so-called keg spiral, and has its outer ends screw threaded, as shown at 23 and 24. Nuts 25, 25, disc. mesh with these screw threads upon the ends of the spiral spring and clasp the respective blocks 20 and i between them.

'l hof operation of my invention is asxfolthe quadrilatera lows: The parts are so designed preferably that when the elliptical spring is deflected, the amount corresponding. to the normal weight which it is to carry, the short stifl spiral spring shall be in a condition of equilibrium without distortion or stress either of compression or distention. When a shock of any kind, suchas is roduced by the wheel passing over an obstac e, causes an abnormal compression of the elliptical spring, the spi ral spring is then immediately thrown into 'a condition of distortion by distention, the

free ends'of the swinging links being forced away from one another by the link action. This enables the spiral spring to assist the elliptical spring in resisting further distor tion. Furthermore, when extreme compression of the elliptical spring occurs, the second spiral or keg shaped spring is actually compressed radially between the approaching halves of the elli tical spring, or the links of I controlled thereby. Said keg-shaped spring being locatedin the same plane as the ]OiIl-te(l system of links is necessarily compressed between them when the quadrilateral is flattened -beyond a certain point. In this way, the spiral or keg-shaped spring interposes the great stiffness and resistance of its coils to radial compression and acts as an ultimate buffer for the load when the main spring is compressed to an extreme degree. 'VVhen the elliptical spring reacts and springs back to a position on the other side of its normal position tending to throw the vehicle up in the air, and also to break the inner unsupported leaves of the elliptical spring by the shock of the recoil, the spiral spring is immediately subjected to a powerful compressing action, which increases rapidly as the degree of separation of the two parts of the elliptical spring increases and this checks therecoil and rebound of the elliptical spring,

protects it from fracture, and produces a great savingin the wear andtear on the vehicle, besides contributing to the comfort of the occupants.

It is evident, of course, that other forms of connecting mechanism might be substituted for the link mechanism to produce the above described result and that different forms of spring might be substituted for the particular form of spiral spring shown.

The invention might be employed with vehicle supporting springs of other than elliptical variety, and various other changes .in the details of construction made without departing from the spirit and scope of my invention. r

'Having described my invention, I claim:

1. In a' supporting dev ice' for vehicles the combination of the main spring, a pair of links pivoted thereto,a still double acting spring connecting the other ends, "of said links, and means for compelling the ends of said links so connected'to the double acting spring to separate one from the other as the main spring is deflected and to approach one anotheras the rnainspring reacts from such deflection. i

2. In a supporting device for vehiclesvthe combination of an elliptical spring, aquadrilateral jointed system of links having 0 )p0- site corners connected to the two parts oi the elliptical, spring and a'second stilfdoubleactings ring connecting the other two cornersof t 1e quadrilateral system i 3; In a supportim device for vehicles the combination'of an elliptical spring, a quadrilateral jointed system of links having opposite corners connected to the two parts of the elliptical spring and a second spring connecting the'other two corners of the quadrilateral system, said second spring being a keg shaped spring of'gre'at stillness, located in the same plane as the jointed system of links.

, 4. In. a supporting spring for yehicles the combination of an elliptical leaf spring, a pan of links pivotally attached to the inner leaf of each side of the spring, two shorthlocks pi'votally connecting the opposite free ends oi the links and a spiral spring connecting: said blocks, said spiral spring having screw threaded ends passing through said blocks, and nutsmeshingw th said threads, each block being clasped between the two nuts on one end of the spiral spring; i t

Signed at New York, NJYQ, this 16 day of March, 1906. i

FRANCIS EDWARD PRATT.

witnesses:

FRANK Olfrimm'm,

G. URAWFORI). 

